Integrating hydrogeological, geophysical, and remote-sensing data to identify fresh groundwater resources in arid regions: a case study from Western Iraq

There is a limited availability of fresh groundwater in the western part of Iraq due to the aridity of the region, and new water supplies are required to meet the demands of potential industrial, mining, and agricultural projects. Consequently, the factors that influence the quality, availability, and distribution of fresh groundwater in the region were assessed by combining hydrogeological, geophysical, and remote-sensing data within a GIS environment. For this purpose, the Shuttle Radar Topography Mission elevation data, geophysical data (gravity and magnetic), and hydrogeological database were used in an integrated approach. It was concluded that both a regionally extensive, deep intergranular aquifer and shallow-fractured and karstified carbonate aquifers have the potential to contain fresh groundwater in the region. It was inferred from the hydrochemical statistics that the main factors controlling groundwater chemistry are the dissolution of evaporite minerals and the weathering of carbonate rocks. Gravity (measured and satellite) data and magnetic data were processed and interpreted to identify the locations and characteristics of subsurface structures. Source Parameter Imaging was applied to calculate depth to the magnetic basement map from gridded magnetic data. The decompensative anomaly maps showed that zones with fresh groundwater are distributed on gravity lows which coincide with areas with a large depth to basement. Most of the fresh groundwater zones in the region are distributed between the pre-Tertiary and Tertiary axes of the Ha’il Arch due to increased recharge along this structure caused by intense fracturing. The extension of the gravity high outside the Iraq territory may suggest similar freshwater zones of groundwater occur in Syria, Jordan, and Saudi Arabia.